The sealing of shipping cartons particularly as is practiced in single passage of the carton through a taping apparatus, involves applying a continuous running length of sealing tape such as a pressure sensitive tape to the carton in a course starting on the carton front wall, around onto a horizontal panel, that is, onto the carton top or bottom, and then onto the carton rear panel where the tape course is terminated. While this practice is probably necessary for taping of cartons carrying contents of reasonably heavy weight and where the carton top and bottom panels are defined by infolded carton flaps abutting at horizontal carton seams, there are many instances where shorter discontinuous tape courses would suffice, thereby resulting in significant savings in the quantity of sealing tape required in connection with carton packing and shipping operations. Representative of such instances are packaging involving use of conventional types of cartons with infolded top and bottom flap members but which are employed for contents packaging of products that is relatively light so that subsequent filled carton handling operations will not result in adverse opening of the infolded top and bottom flaps if same are secured along seams with discontinuous tape lengths rather than with continuous lengths running along the full horizontal seam and onto both the front and rear carton panels. Another instance where effective tape securement can be achieved with discontinuous or discrete tape lengths is the use of telescopic type cartons where for example, a rectangular carton base is filled with product and a companion rectangular cover member is telescoped over the base and tape sealed thereto. The tape courses or runs with which such cartons can be sealed could follow "J" or "L" tape runs at the carton front and rear ends, the "J" or "L" defining the discrete tape run length from a front or rear panel onto a horizontal panel. While many types of tape sealing machines which tape in a continuous course from front to rear on a traveling carton are known to the present inventors, and while taping devices for applying a "J" or "L" tape course around a single carton or box corner onto two intersecting panels are known to them, they are not aware of any prior embodiment in taping apparatus of any means which allows simply achieved and effective tape sealing of "J" or "L" tape courses at both the front and rear of a carton as it travels in a single passage through taping apparatus.